During assembly of an aircraft, certain operations are performed synchronously on opposite sides of a structure. Consider a fastening operation on a wing box. A robotic system outside the wing box performs drilling, countersinking and fastener insertion tasks. A person inside the wing box supports these tasks, and also places a sleeve and nut over the inserted fastener while the robotic system is holding the fastener.
It would be desirable to eliminate the manual labor and fully automate such a fastening operation. Yet while placing a nut over the threads of a bolt might be a simple task for a human, it is not so simple for a robotic system. Precise positioning and orientation of a nut over a bolt is a complex task.
This task is even more complex because a robotic system would have to attach the nut in a confined space. The task is even more complex because the robotic system would have to enter the confined space via an access hole. The task is even more complex because aircraft tolerances are extremely tight. The task is even more complex because the robotic system inside the confined space has to synchronize its tasks with those of the robotic system outside the confined space.